Crews had been focusing on Peirce Island in Portsmouth, but on Wednesday, boats headed up the river toward Newington.

Prosecutors said Marriott was killed on Oct. 9. Crews have been searching the Piscataqua River and its tributaries for her body for 12 days.

Investigators said they have credible evidence that Marriott's body is in the river. Seth Mazzaglia, 30, has been arrested and charged with second-degree murder.

On Wednesday morning, two boats from Marine Patrol combed the waters off Fox Point in Newington.

The day before, divers were brought in for the first time to search the river close to the shore of Peirce Island.

The search has been expanding. The attorney general's office said that on Monday, searchers went as far south as Cape Ann in Massachusetts. Marine Patrol is analyzing tidal patterns to determine where to search next.

Marine Patrol is being assisted by a boat from the Newington Fire Department.

The Obama administration will unveil a major climate change plan Monday aimed at a large reduction in greenhouse gas emissions from the nation's coal-burning power plants, a senior administration official told CNN.